Macrophages are also identified in the spiral ligament, spiral limbus and neural regions. of the basilar membrane. As the sensory epithelium matures, these cells undergo developmental death with the phenotypes of apoptosis. Macrophages are also recognized in the spiral ligament, spiral limbus and neural regions. Their numbers decrease during postnatal development. Together, these results suggest a dynamic rearrangement of the macrophage populace during postnatal cochlear development. test, one-way or two-way ANOVA (see the Results section for details) using SigmaStat (Version 3.5) (San Jose, CA, USA) or GraphPad Prism (Version 5) (La Jolla, CA, USA). An -level of 0.05 was selected for significance for all those statistical assessments. 3. Results Immune cells were recognized using immunolabeling of F4/80 (a macrophage marker protein), Iba1 (a macrophage marker protein), Ly6C (a monocyte marker protein) and CD45 (a pan-leukocyte marker). The tissues were stained with either one or two antibodies to identify immune cells. Because the immunoreactivity of CD45 was much stronger than Oxytocin Acetate that of other marker proteins, we used CD45 staining to illustrate macrophage morphology in the current study. 3.1. The basilar membrane and the organ of Corti contain immune cell populations The cochlear whole-mount sensory epithelium preparation contains CD45-positive cells in multiple tissue partitions (Fig. 1A). We first examined the CD45-positive cells in the organ of Corti and the basilar membrane. To determine the precise location of CD45-positive cells, we double-stained the tissues with PI or DAPI to illustrate nuclei or with an Ceftriaxone Sodium antibody against Itga3 to illustrate the basement membrane. Using confocal microscopy, we found that CD45-positive cells were present in two locations relevant to the mesothelial cells and the basement membrane. One was around the scala tympani side of mesothelial cells (Fig. 1B). The other Ceftriaxone Sodium was around the organ of Corti side of the mesothelial cells (Fig. 1B and C). Some of these cells were found between the cells of the organ of Corti and the basement membrane (Figs. 1C and 1D) as well as others were found along the spiral vessels (Figs. 1B and 1E). Noticeably, the cells in different locations underwent unique developmental changes and experienced different fates that will be explained Ceftriaxone Sodium in the following sections. Open in a separate window Physique 1 Distribution of CD45-positive cells in the basilar membrane and the organ of Corti= 22.3; df = 2,36; 0.001; Tukey test: P1-4 vs. P10, = 0.006; P10 vs. P17-21, = 0.005). The analysis also revealed that the average number of CD45-positive cells in the apical region (31.9 11.7) was slightly, but statistically, higher than those in the middle and basal regions (24.1 8.2 and 22.4 8.3; = 6.5, df = 2,36; = 0.004; Tukey test: apical region vs middle region: = 0.005; apical region vs. basal region: = 0.023; Fig. 2B). To determine the identity of CD45-positive cells, we doube-stained the tissues with CD45 and F4/80 or with CD45 and Iba1. The immunoreactivity of F4/80 and Iba1 was detectable at P1 and their immunoreactivity became stronger at later time points (Fig. 3). The majority of CD45-positive cells (80% 9) display strong F4/80 and Iba1 immunoreactivity, suggesting that these cells are macrophages. Open in a separate window Physique 2 Comparisons of the numbers of CD45-positive cells among different postnatal periods and anatomic sites of the basilar membrane= 22.3; df = 2,36; 0.001; Tukey test: P1-4 vs. P10, = 0.006; P10.